Taxonomic Revision of Adiantum ser. Venusta Ching (Pteridaceae) from Pan Himalayas*

Based on morphological study of specimens and extensive fieldwork, with the analysis of the micromorphology and phytogeographic materials, the series Venusta of Adiantum from Pan Himalayas was taxonomically revised. It turns out that the shapes of indusia on fertile pinnules and the morphological characteristics of apical serrations on ultimate pinnules and the microstructures of scales are the most important characters for species identification. Seven species and two varieties were recognized from Pan Himalayas: Adiantum roborowskii, A. roborowskii var. robustum, Abonatianum, Afengianum, Afimbriatum, Adavidii, Adavidii var. longispina, Avenustum and Atibeticum. Three published names were reduced to synonyms: Adiantum breviserratum was synonym of Afimbriatum, Adiantum erythrochlamys was synonym of Aroborowskii var. robustum and Adiantum bonatianum var. subaristatum was synonym of Abonatianum.